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Richard Yao ab8d9c1783 Cleanup: 64-bit kernel module parameters should use fixed width types
Various module parameters such as `zfs_arc_max` were originally
`uint64_t` on OpenSolaris/Illumos, but were changed to `unsigned long`
for Linux compatibility because Linux's kernel default module parameter
implementation did not support 64-bit types on 32-bit platforms. This
caused problems when porting OpenZFS to Windows because its LLP64 memory
model made `unsigned long` a 32-bit type on 64-bit, which created the
undesireable situation that parameters that should accept 64-bit values
could not on 64-bit Windows.

Upon inspection, it turns out that the Linux kernel module parameter
interface is extensible, such that we are allowed to define our own
types. Rather than maintaining the original type change via hacks to to
continue shrinking module parameters on 32-bit Linux, we implement
support for 64-bit module parameters on Linux.

After doing a review of all 64-bit kernel parameters (found via the man
page and also proposed changes by Andrew Innes), the kernel module
parameters fell into a few groups:

Parameters that were originally 64-bit on Illumos:

 * dbuf_cache_max_bytes
 * dbuf_metadata_cache_max_bytes
 * l2arc_feed_min_ms
 * l2arc_feed_secs
 * l2arc_headroom
 * l2arc_headroom_boost
 * l2arc_write_boost
 * l2arc_write_max
 * metaslab_aliquot
 * metaslab_force_ganging
 * zfetch_array_rd_sz
 * zfs_arc_max
 * zfs_arc_meta_limit
 * zfs_arc_meta_min
 * zfs_arc_min
 * zfs_async_block_max_blocks
 * zfs_condense_max_obsolete_bytes
 * zfs_condense_min_mapping_bytes
 * zfs_deadman_checktime_ms
 * zfs_deadman_synctime_ms
 * zfs_initialize_chunk_size
 * zfs_initialize_value
 * zfs_lua_max_instrlimit
 * zfs_lua_max_memlimit
 * zil_slog_bulk

Parameters that were originally 32-bit on Illumos:

 * zfs_per_txg_dirty_frees_percent

Parameters that were originally `ssize_t` on Illumos:

 * zfs_immediate_write_sz

Note that `ssize_t` is `int32_t` on 32-bit and `int64_t` on 64-bit. It
has been upgraded to 64-bit.

Parameters that were `long`/`unsigned long` because of Linux/FreeBSD
influence:

 * l2arc_rebuild_blocks_min_l2size
 * zfs_key_max_salt_uses
 * zfs_max_log_walking
 * zfs_max_logsm_summary_length
 * zfs_metaslab_max_size_cache_sec
 * zfs_min_metaslabs_to_flush
 * zfs_multihost_interval
 * zfs_unflushed_log_block_max
 * zfs_unflushed_log_block_min
 * zfs_unflushed_log_block_pct
 * zfs_unflushed_max_mem_amt
 * zfs_unflushed_max_mem_ppm

New parameters that do not exist in Illumos:

 * l2arc_trim_ahead
 * vdev_file_logical_ashift
 * vdev_file_physical_ashift
 * zfs_arc_dnode_limit
 * zfs_arc_dnode_limit_percent
 * zfs_arc_dnode_reduce_percent
 * zfs_arc_meta_limit_percent
 * zfs_arc_sys_free
 * zfs_deadman_ziotime_ms
 * zfs_delete_blocks
 * zfs_history_output_max
 * zfs_livelist_max_entries
 * zfs_max_async_dedup_frees
 * zfs_max_nvlist_src_size
 * zfs_rebuild_max_segment
 * zfs_rebuild_vdev_limit
 * zfs_unflushed_log_txg_max
 * zfs_vdev_max_auto_ashift
 * zfs_vdev_min_auto_ashift
 * zfs_vnops_read_chunk_size
 * zvol_max_discard_blocks

Rather than clutter the lists with commentary, the module parameters
that need comments are repeated below.

A few parameters were defined in Linux/FreeBSD specific code, where the
use of ulong/long is not an issue for portability, so we leave them
alone:

 * zfs_delete_blocks
 * zfs_key_max_salt_uses
 * zvol_max_discard_blocks

The documentation for a few parameters was found to be incorrect:

 * zfs_deadman_checktime_ms - incorrectly documented as int
 * zfs_delete_blocks - not documented as Linux only
 * zfs_history_output_max - incorrectly documented as int
 * zfs_vnops_read_chunk_size - incorrectly documented as long
 * zvol_max_discard_blocks - incorrectly documented as ulong

The documentation for these has been fixed, alongside the changes to
document the switch to fixed width types.

In addition, several kernel module parameters were percentages or held
ashift values, so being 64-bit never made sense for them. They have been
downgraded to 32-bit:

 * vdev_file_logical_ashift
 * vdev_file_physical_ashift
 * zfs_arc_dnode_limit_percent
 * zfs_arc_dnode_reduce_percent
 * zfs_arc_meta_limit_percent
 * zfs_per_txg_dirty_frees_percent
 * zfs_unflushed_log_block_pct
 * zfs_vdev_max_auto_ashift
 * zfs_vdev_min_auto_ashift

Of special note are `zfs_vdev_max_auto_ashift` and
`zfs_vdev_min_auto_ashift`, which were already defined as `uint64_t`,
and passed to the kernel as `ulong`. This is inherently buggy on big
endian 32-bit Linux, since the values would not be written to the
correct locations. 32-bit FreeBSD was unaffected because its sysctl code
correctly treated this as a `uint64_t`.

Lastly, a code comment suggests that `zfs_arc_sys_free` is
Linux-specific, but there is nothing to indicate to me that it is
Linux-specific. Nothing was done about that.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Original-patch-by: Andrew Innes <andrew.c12@gmail.com>
Original-patch-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13984
Closes #14004
2022-10-13 10:03:29 -07:00
.github CI: bump actions/upload-artifact to v3 2022-10-12 15:18:39 -07:00
cmd Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
config Linux: Remove ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST autotools check 2022-10-13 10:03:09 -07:00
contrib PAM: Fix unchecked return value from zfs_key_config_load() 2022-10-05 17:09:24 -07:00
etc etc: mask zfs-load-key.service 2022-10-12 15:27:55 -07:00
include Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
lib Handle possible null pointers from malloc/strdup/strndup() 2022-10-06 17:18:40 -07:00
man Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
module Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
rpm Add zilstat script to report zil kstats in a user friendly manner 2022-09-02 13:24:07 -07:00
scripts scripts/enum-extract.pl should not hard code perl path 2022-10-11 12:32:07 -07:00
tests Cleanup: 64-bit kernel module parameters should use fixed width types 2022-10-13 10:03:29 -07:00
udev Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore autoconf: use include directives instead of recursing down cmd 2022-05-10 10:18:38 -07:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
AUTHORS Introduce BLAKE3 checksums as an OpenZFS feature 2022-06-08 15:55:57 -07:00
autogen.sh autogen.sh: paper over automake <1.14's lack of %reldir% support 2022-05-10 10:20:46 -07:00
CODE_OF_CONDUCT.md Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
configure.ac Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
copy-builtin copy-builtin: add hooks with sed/>> 2022-05-10 10:17:43 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Replace EXTRA_DIST with dist_noinst_DATA 2022-05-26 09:24:50 -07:00
META Linux 5.19 compat: META 2022-08-02 10:04:38 -07:00
NEWS Fix NEWS file 2020-08-26 21:44:41 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md README: Update OpenZFS website url 2022-01-06 16:25:01 -08:00
RELEASES.md Add RELEASES.md file 2021-04-02 16:33:40 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.